Sparking plug



R. F. HALL. SPARK Nc PLUG FlLED MAY 24,

Jan. 30, 1923.

per

Patented dan. 30, 1923.

UNITED STATES ROBERT FREDERICK HALL, OF MOSELEY, NEAR BIRMINGHAM,ENGLAND.

srAnKING PLUG.

Application filed May 24, 1920. Serial No. 383,830.

To all wwmit may concern:

Be it known that ROBERT FREDERICK. HALL, a subject ot the King of GreatBritain and llreland, residing at Moseley, near Birmingham, in thecounty of Warwick, England, have invented certain new and usefulImprovements in Sparking Plugs; and l do hereby declare the following tobe a full, clear, and exact description of the invent-ion, such aswillenable others skilled in the art to which it appertains to make and usethe same.

rl`his invention relates to sparking plugs 'for internal combustionengines and is designed to provide devices of the class in questionwhich are morev efficient in use, more economical and possess otheradvantages as comparedrwith sparking plugs as at present in use.

@ne of the principal objects ot the invention is to provide a pluginwhich both the electrodes or sparking points are furnished in a bodyadapted to be placed in a casing permanently ,attachable to the engine,so that the said body .can be easily removed for the purposes ofcleaning the sparking points, or jfor replacing it by or interchangingit for a different body to suit requirements.

Another object of the invention is to provide improved means for coolingor ventilating the plug.

A further object ot the invention is to provide an eilicient gas tightjoint to the plug, in spite of the carrying temperatures to which it isexposed, and irrespective of the fact that the insulator body carryingboth the electrodes can beveasily removed.

A further object is to provide means for adjusting with great accuracythe dimensions ot the spark gap to `suit requirements.

Other objects or' the invention will be hereinafter mentioned withreference to the particular constructional embodiments of the saidinventions shown on the accom pauying drawing.

In order that the said invention may be clearly understood, 1 willproceed to describe the saine with reference to the accompany ingdrawing, in which v Fig. 1 is a vertical axial section of a sparkingplug constructed according to the primary method of carrying out niyinven, tion.

vno sparking point Fig. 2 is an elevation of the same plug.

detached.

Fig. et is a plan of the same. Fig. 5 is an elevation of the tube enclosing the insulated electrode.

Fig. 6 is a plan of same.

Fig. 7 and Fig. 8 are elevation and plan respectively of a castellatedring serving to retain the insulated electrode in its adjusted position.

Fig. 9 is a view ot the ferrule carrying the earthed electrode.

Fig. 10 is a view of the sparking point detached from the Jerrule.

Fig. 11 and Fig. 12 are vertical section 4and plan respectively of thecap for rethe insulated electrode and otherv taining parts in positionin the outer body.

Fig. 13 is a separate view of the insulated electrode.

Fig. 14 is a sectional view of a modified -torni of plug.

Fig. 15 shows the carrier for the insulated and earthed electrode otFig. 14 removed from the outer body.

Fig. 16 is a horizontal section ofthe central sparking point, and

Fig. 17 is a view similar further modification.

Figs. 18 and 19 are views of modified forms ot block to which the end ofthe high tension cable is attached.

he same numerals of reference are 7employed to denote the same parts inall the views.

Referring to the constructionv shown in Figs. 1 to 13, the main or outerbody 1 of the sparking plug is .formed from hexagon section drawn steel7provided with fins 2 for facilitating the radiation and cooling, andwith holes 3, drilled through the flats;

The end l ofthe body 1 is machined down to form a thread so that it isadapted to screw into the cylinder Wall. T he main plug body may remainpermanently 1n position as or electrode is rigidly bo Fig. 15 of aconnected thereto.

The main body 1 is tubular end is pro vvided at 5 with an annular valvelike seating machined inrnallyv near the screw threaded end t. (l is ascrew thread, at the upper end of the body 1 to receive the refv,taining cap hereinafter mentioned,

' is channel 12 extending fronrits upper end to.

i rat/ely in Fig. 9.

The' detachable. insulator body, is

,adapted to t into the main body l., just described is. constructed lasfollows 7 is a piece of round steel having drilled holes at each end.@ne of these holes 8 is adapted to receive a nickel sparking 'point 8a(Fig. 13) constituting the central or vin sulated electrode. This sarkin'@1 `point is preferably made from nickel rod, or wire, one end ofwhich forms a tight fit'in thehole 8 whilst towards its oppositeMend-itis cranked at 8b for a .purpose hereinafter described.

The other hole 9 at the opposite end of the member 7 is adapted .toreceive the terminal plug'of the high tension electrode.

" Round the central steel body 7 is coiled l' or folded a thinstrip-.ofinica 10, until an insulating covering ofthe required thick-vness and diameter is formed, or some other.

insulating material may take the place of the mica if desired.

l 11 is a steel tube shown. se arately in Figs. 5 and t3 over the micaor ot er'insulation 10 and to form a firmly attached outer covering orretainer when pressed, shrunk or otherw wise xed in position.

rlhe outer surface of the tubular body 11 provided with a longitudinalgroove or within a short distance of its lowerend 13, the latter beingturned` with a valve like seating corresponding substantiallyto thebefore mentioned seating 5,-on the main bodyl. The upper end ofthe tube11 is `provided with a flat facing at 14 upon which the retaining cap isadapted to press.

15 is an open ended ferrule vsho-wn sepaadapted to fit over the outsideof the lower end of the tube 11 and is preferably made of steel conformssubstantially ,tothe lower end of said-tube andis provided with astepped portion at .1 6 corresponding to and adapted to begrippedbetween the valve like seating 5 and 13 on the casingl and thetibe 11 relispectiv'ely. lits vlower end is out od at a sharp angle at15a andat or near its lower endl 'is drilled to` receive a nickelsparking point 17 10) which ts into said hole and v'riveted or otherwisesecured in position as shown in Fig. 1, so as to project inwardlytowards the central insulated lelectrode 8a.

1S is a projecting point or tooth in theupper edge of the ferrule 15 fora purpose herein# engage the tooth or afterenplained. .19 (rFigs. 7and8) is a ring or bush adapted to fit over. the outer surface of thetube 11, the Alower endof which is formed with a series'of castellations20, the grooves of whichfare of sufficient width to oint 18 on the upperedge ofthe ferrule. ne o f theteeth of the castellations is bentinwardly as shown at 20a to engage the longitudinalV groove 12, on theouter surface of the tube 11, lso that the This ferrule which isteniente tube 11, the ferrule 15 and the ring 19 are locked togetherrelatively to one another. By this means the length of the spark gapbetween the sparking point 17 on the ferrule 18 and the end of thecentral sparkin point 8a may be adjusted byrst lifting t e casltellatedring 19 upwardly untif the tooth or point 18 on the ferrule is free .ofthe 'castellations and on rotating the ring 19, the tubular memberllcarryingtheinsulateol central electrode will also-be rotated, and asthe end 'of the/sparkingpoint 8@ is located eccentri" retaining capwhich is of stepped tubular form externally screw-.threaded at 22 toengage the screwed portion 6 of the body 1 and internally screwed at'23to receive a screwed cap or ada tor 2lirlhe retaining cap 21 is,provided with an internal flange or shoulder 21a adapted to engage theupper flat surface 1d of the tube 11`and with a central perform` tion21'b through which the mica or other in-y sulation 10 projects.

The u per Aouter surface of' the screwed to"facilitateits attachment.Within the cap 'cap or a aptor 24 is milled or'knurled at 2te 24 isplaced a block of insulating material 25 say 4for instance vulcanizedfibre, which is provided with a central recess, the lower end of whichis stepped at 26 whilst the upper portion of said'recess may be taperedat 27 to receive the end ofthe long-extension cable 28 from the magnetoor coil.' .The latter is secured in the following manner. The ends oftheupper strands and the cable are cut off flush atl 29 and then a smallwire plug terminal 30 is screwed up into the cableamong thecopperstrands-thereby swelling 'out the end of the cable as seen clearlyin Fig. 1 and making it of larger diameter than the remaining portion sothat it will not pull through the hole in the block 25 and so that anypull`-onlytends tocau'se the end ofthe cable to be gripped more tightly.

The hole 9 is preferablydrilled deeper than the length of the projectingterminal to allow for any variation in length in the manufacture of thedierent parts.

lt will be seen that withthe foregoing (construction, access maybereadily obtained to the body carrying both electrodes for the purposeofJ cleaning adjusting inspectingor replacing the'same, as when theretaining v w @er 2l .is unscrewed. the tube ll With the centralinsulated electrode and the errule carrying the earthed electrode mayeach be removed Without removing the main or other body 1. Jrom theengine cylinder' and Without detaching the high tension cable from theadaptor 24 andblock 25.

Referring novv to the construction shown in lFigs. lil, 15 and 16, itwill be seen that the tube 11 and the errule 15 have been combined toform one member carrying the earthed electrode. ln this construction theferrule like inmebr 31 is biturcated at its lower end at 82. fit or nearthe lower end of each arm is provided a spherical or other appropriatelyshaped sparking point 33 riveted or otherwise secured in position asshovvn in Fig. 15. rlhe central member 7 forming the central insulatedelectrode is in this construction formed with a central rod the lowerend oit -which is screw-threaded to receive a nic tel sparking point 35consisting of a plug or the like, the outer sui-tace of which is steppedor formed with two earn like surfaces 35% 35 arranged in such a manneras to enable tbe'lengtli of the spark gap to be adiusted by rotationoi'l the plug 35, by increasingA o`^ decreasing the distance .y

between the sparkino point 33 or' the earthed electrodes and the pointsof nearest approach on the cani like surfaces 35a.

The hi gli tension cable 28 in this construction is attached a llibreblock 36 in the manner already described., but in order to enable theretaining' cap to be screwed dovvn or the screwed cap or adaptor 3"? canrving tbe high tension cable tc be Without twisting the cable erotlerivise loosening by tbe connection between the 'Wire terminal 30nthe outer surface c.. tbe nbre block 36 is encased in a 'ferrule 38 oity this i he screwed i cli forms a sl retainingn is rotated adaptor *e'll i curely hold ie 28 in position. has the iii the high tension cableend o1 ihrs method of attachment ner s lvantage that once the end .'1.Lh 01,@ a EL? ya .L Y 1. 1 o 10D, or t e cable wie@ i le terminali nasbeen secured positi *i in the block E@ will not need to be detached andthe cap 2l may be eas ly removed from 1 and remain attached to theadaptor 57 tbe cable 28 when the electrodes are be' removed thus savinguconsiderable e prevent tne loss or damage to Lne darts.)

which orte happens with pings as present constructed.

The construction sliovvn in lar to that shown screwed like centralreplaced bv a spherical with a central ce" "l duced of tbe central endo'f the latter being' riveted over so as to retain the sparking point inposition. In this form the adjustment of the spark gap is effected bvspringing or bending the bifurcated ends or arms 32 towards or away fromthe central insulated electrode.

Figs. 18 and 19 show two modified forms ot blocks of insulating materialto which the end of the high tension cable 28 is attached.. ln the formshown in llig. '18 the block 25a is formed with an enlarged recess 26eX- tending upwardly from the bottom surface whilst the central holeistapered at 27 as in the construction shown in TEig. 1. The end of thehigh tension cable 28 is 'secured in the plug 25a in a similar manner tothat described in connection with Fig. 1 Whilst the lower outer surfaceof tbe recess 2o@ forms a. skirt when the plug is assembled which,surrounds and protects the upper edge of the insulating' covering l0 ofthe central electrode. rlhe form shovvn in Fig. 19 representsalternative ofviibre porcelain or other insulating material Wliicb.

high tension cable in the usual manner by an eY epiece eneaoin@ thescrewed rod i in, n c;

ln this con traction the block 25D is provided with a centraf. recess,as in the previous construction 1vhilst the central electrode terminalBO is extended upwardly through tlie top of tile o u@ and is formed witha square or other s" Q abiT shaped shoulder-, ttinfsu ^riy shaped holein tLe block 25h 1 L i 1m "i end ofi tne cabie is connected thereto,Whilst r: n v

block is rorined with a ateiy entendingg neck gecting through ie liolein the secure the United of insulating material.7 a which ii-isuletininred a errule carrying" said nd havinga valve like portion fo engage thein the cody po sparking point on said ferrule "for securing` saidtubular ne lengtn of the spa-rk or dinsted.

"i plug, tbe combination ci a body 'portion provided internally Willivalve like seatingj a central electrode carrier1L by a coveringinsulating1 material, a t bular member in which said insulating); covissecureda a errule said tubular and having; a valve like tion lapted toengage tbe seating in norand desire i rule awa-inst independent ro-.

Toofiy gportkionf sparking point on said fenn rule, a spanking ponit'onsaid central' electrode,a projection on said. fer-rule., a locking o.ring surrounding seid tubular member, a,

5,projecifnonon seid lockingringengaging a, longitudinal groove in saidtubular member and. spaced recesses on saidlocking ring., coy nonnenmnnnnieinmn.

